SNES hardware clones

Discussion of hardware and software development for Super NES and Super Famicom.

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Jagasian
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SNES hardware clones

Post by Jagasian » Thu Sep 13, 2012 1:18 pm

Why are the SNES clones so much more accurate than the NES clones? What are the known issues / flaws in the popular SNES clones being sold today?

tepples
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Re: SNES hardware clones

Post by tepples » Thu Sep 13, 2012 3:27 pm

Jagasian wrote:Why are the SNES clones so much more accurate than the NES clones?
Let me take a guess or four:
  • RGB palette. No emphasis crap to deal with. Some Russian famiclones have a problem with tint bits, giving a lot of games a green cast like the Matrix.
  • No external video memory. Everything that is displayed is copied into the PPU's 64 KiB of RAM, unlike the NES where carts can add 4-screen mirroring or fetch-triggered bank switching effects such as MMC2/4 backgrounds or MMC5 separate sprite banks.
  • Cycle accuracy is not quite as necessary on Super NES due to multiple layers for status bars and HDMA for raster effects. Games requiring cycle-accurate sync with a coprocessor tend to be unplayable anyway due to CIC handshake failure.
  • Super famiclones tend to be exact copies, unlike NOACs whose makers feel the need to add "enhanced" modes like OneBus and greater bit depth to make up for limitations in the NES architecture.

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MottZilla
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Re: SNES hardware clones

Post by MottZilla » Thu Sep 13, 2012 5:41 pm

From what I've heard one reason is the actual circuit design of the SNES may have made it easier to clone than the NES. I recall someone saying something about various bits, being analog on the NES where as SNES is pretty much digital all the way. I forget who said it. But apparently SNES clones seem to be pretty accurate, some do play the games with coprocessors just fine.

tepples
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Re: SNES hardware clones

Post by tepples » Fri Sep 14, 2012 4:42 am

The only things that are analog about the NES are the amplification paths starting at the video DAC and the audio DAC. Failing at Castlevania 3 is unrelated to any difference in these analog stages.

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kyuusaku
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Re: SNES hardware clones

Post by kyuusaku » Fri Sep 14, 2012 2:03 pm

The SNES is made of static CMOS logic, the NES is made of dynamic NMOS logic. I think they just did a better job with the SNES lithography, which as static logic is probably less process critical. There's also the issue of external wiring which is simpler on the SNES. Lastly AFAIK there's only one set of cloned SNES chips, the NES dies were cloned at least a handful of times, some more successfully than others.

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